U.S. patent number 8,688,131 [Application Number 13/461,439] was granted by the patent office on 2014-04-01 for apparatus and methods for facilitating simulcasting and de-simulcasting in a distributed antenna system.
This patent grant is currently assigned to QUALCOMM Incorporated. The grantee listed for this patent is Rashid Ahmed Akbar Attar, Christopher Gerard Lott, Rohan Salvi, Joseph B. Soriaga. Invention is credited to Rashid Ahmed Akbar Attar, Christopher Gerard Lott, Rohan Salvi, Joseph B. Soriaga.
United States Patent |
8,688,131 |
Soriaga , et al. |
April 1, 2014 |
Apparatus and methods for facilitating simulcasting and
de-simulcasting in a distributed antenna system
Abstract
An RF connection matrix may include first and second
carrier-specific RF connection matrix modules. The first
carrier-specific RF connection matrix module can be adapted to
route a first downlink transmission to one or more remote antenna
units for transmission on a first carrier. The second
carrier-specific RF connection matrix module can be adapted to
route a second downlink transmission to one or more remote antenna
units for transmission on a second carrier. Methods for
facilitating simulcasting and de-simulcasting may include receiving
a signal associated with a sector ID, which signal includes a first
downlink transmission for a first carrier and a second downlink
transmission for a second carrier. The first downlink transmission
can be routed to one or more remote antenna units for transmission
on the first carrier. The second downlink transmission can be
routed to one or more remote antenna units for transmission on the
second carrier.
Inventors: |
Soriaga; Joseph B. (San Diego,
CA), Lott; Christopher Gerard (San Diego, CA), Attar;
Rashid Ahmed Akbar (San Diego, CA), Salvi; Rohan (San
Diego, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Soriaga; Joseph B.
Lott; Christopher Gerard
Attar; Rashid Ahmed Akbar
Salvi; Rohan |
San Diego
San Diego
San Diego
San Diego |
CA
CA
CA
CA |
US
US
US
US |
|
|
Assignee: |
QUALCOMM Incorporated (San
Diego, CA)
|
Family
ID: |
47148936 |
Appl.
No.: |
13/461,439 |
Filed: |
May 1, 2012 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20130094454 A1 |
Apr 18, 2013 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61547639 |
Oct 14, 2011 |
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61576836 |
Dec 16, 2011 |
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Current U.S.
Class: |
455/447; 370/343;
370/401 |
Current CPC
Class: |
H04B
7/0691 (20130101); H04W 16/12 (20130101); H04B
7/12 (20130101); H04W 72/046 (20130101); H04W
72/042 (20130101) |
Current International
Class: |
H04J
1/00 (20060101); H04W 40/00 (20090101) |
Field of
Search: |
;370/252,328,329,343,344,400,401,431,463-465,468
;455/445-447,450,451 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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9820619 |
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May 1998 |
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WO |
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2004032548 |
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Apr 2004 |
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WO |
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2010093613 |
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Aug 2010 |
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WO |
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2012024345 |
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Feb 2012 |
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WO |
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Other References
Chakrabarti A., et al., "Repeaters and Remote Radioheads in EVDO
Networks", Vehicular Technology Conference Fall (VTC 2010-FALL),
2010 IEEE 72nd, IEEE, Piscataway, NJ, USA, Sep. 6, 2010, pp. 1-6,
XP031770505, ISBN: 978-1-4244-3573-9. cited by applicant .
International Search Report and Written
Opinion--PCT/US2012/060075--ISA/EPO--Jan. 2, 2013. cited by
applicant .
Ni, J., et al., "Distributed Antenna Systems and Their Applications
in 4G Wireless Systems", Communications Workshops (ICC), 2011 IEEE
International Conference on, IEEE, Jun. 5, 2011, pp. 1-4,
XP031909310, DOI: 10.1109/ICCW.2011.5963593 ISBN:978-1-61284-954-6.
cited by applicant.
|
Primary Examiner: Rose; Kerri
Parent Case Text
CLAIM OF PRIORITY UNDER 35 U.S.C. .sctn.119
The present application for patent claims priority to Provisional
Application No. 61/547,639 entitled "Base Station Modem
Architecture for Simulcasting and De-Simulcasting in a Distributed
Antenna System" filed Oct. 14, 2011, and assigned to the assignee
hereof and hereby expressly incorporated by reference herein. The
present application for patent also claims priority to Provisional
Application No. 61/576,836 entitled "Devices, Methods, and Systems
for Simulcasting in Distributed Antenna Systems (DAS) to Improve
Network Utilization" filed Dec. 16, 2011, and assigned to the
assignee hereof and hereby expressly incorporated by reference
herein.
Claims
What is claimed is:
1. An RF connection matrix employable with a distributed antenna
system, the RF connection matrix comprising: a first
carrier-specific RF connection matrix module adapted to route a
first downlink transmission to one or more remote antenna units for
transmission on a first carrier, wherein the first carrier-specific
RF connection matrix module is adapted to simulcast the first
downlink transmission on the first carrier over a first group of
two or more remote antenna units employing a sector identity (ID);
and a second carrier-specific RF connection matrix module adapted
to route a second downlink transmission to one or more remote
antenna units for transmission on a second carrier, wherein the
second carrier-specific RF connection matrix module is adapted to
simulcast the second downlink transmission on the second carrier
over a second group of two or more remote antenna units employing
the sector ID, wherein at least one remote antenna unit of the
second group differs from the remote antenna units of the first
group.
2. The RF connection matrix of claim 1, further comprising: at
least one carrier separation filter communicatively coupled to the
first and second carrier-specific RF connection matrix modules, the
at least one carrier separation filter adapted to: receive a signal
associated with a sector identity (ID), the signal including
downlink transmissions for at least the first carrier and the
second carrier; convey downlink transmissions for the first carrier
to the first carrier-specific RF connection matrix module; and
convey downlink transmissions for the second carrier to the second
carrier-specific RF connection matrix module.
3. The RF connection matrix of claim 1, further comprising: at
least one carrier combine filter associated with a respective
remote antenna unit and communicatively coupled to the first
carrier-specific RF connection matrix module and to the second
carrier-specific RF connection matrix module.
4. The RF connection matrix of claim 1, wherein the first
carrier-specific RF connection matrix module and the second
carrier-specific RF connection matrix module are adapted to
simulcast downlink transmissions over the plurality of remote
antenna units, wherein at least one of the remote antenna units is
positioned so that a coverage area associated with the at least one
remote antenna unit is not adjacent to a coverage area associated
with any of the other remote antenna units of the plurality.
5. A method operational on an RF connection matrix, comprising:
receiving a signal associated with a sector identity (ID), the
signal including a first downlink transmission for transmission on
a first carrier and a second downlink transmission for transmission
on a second carrier; routing the first downlink transmission to a
first group of two or more remote antenna units for simulcasting
the first downlink transmission on the first carrier over the first
group of two or more remote antenna units employing the sector
identity (ID); and routing the second downlink transmission to a
second group of two or more remote antenna units for simulcasting
the second downlink transmission on the second carrier over the
second group of two or more remote antenna units employing the
sector ID, wherein at least one remote antenna unit of the second
group differs from the remote antenna units of the first group.
6. The method of claim 5, further comprising: conveying the first
downlink transmission for the first carrier to a first
carrier-specific RF connection matrix module; and conveying the
second downlink transmission for the second carrier to a second
carrier-specific RF connection matrix module.
7. The method of claim 5, further comprising: combining the first
downlink transmission and the second downlink transmission into a
signal for at least substantially simultaneous transmission by a
remote antenna unit.
8. The method of claim 5, wherein routing the first downlink
transmission to one or more remote antenna units comprises:
simulcasting the first downlink transmission over a plurality of
remote antenna units, wherein at least one of the remote antenna
units is positioned so that a coverage area associated with the at
least one remote antenna unit is not adjacent to a coverage area
associated with any of the other remote antenna units of the
plurality.
9. The method of claim 5, wherein routing the second downlink
transmission to one or more remote antenna units comprises:
simulcasting the second downlink transmission over a plurality of
remote antenna units, wherein at least one of the remote antenna
units is positioned so that a coverage area associated with the at
least one remote antenna unit is not adjacent to a coverage area
associated with any of the other remote antenna units of the
plurality.
10. An RF connection matrix, comprising: means for receiving a
signal associated with a sector identity (ID), the signal including
a first downlink transmission for transmission on a first carrier
and a second downlink transmission for transmission on a second
carrier; means for routing the first downlink transmission to a
first group of two or more remote antenna units for simulcasting
the first downlink transmission on the first carrier over the first
group of two or more remote antenna units employing the sector
identity (ID); and means for routing the second downlink
transmission to a second group of two or more remote antenna units
for simulcasting the second downlink transmission on the second
carrier over the second group of two or more remote antenna units
employing the sector ID, wherein at least one remote antenna unit
of the second group differs from the remote antenna units of the
first group.
11. The RF connection matrix of claim 10, further comprising: means
for conveying the first downlink transmission for the first carrier
to a first carrier-specific RF connection matrix module; and means
for conveying the second downlink transmission for the second
carrier to a second carrier-specific RF connection matrix
module.
12. The RF connection matrix of claim 10, further comprising: means
for combining the first downlink transmission and the second
downlink transmission into a signal for at least substantially
simultaneous transmission by a remote antenna unit.
13. The RF connection matrix of claim 10, wherein routing the first
downlink transmission to one or more remote antenna units
comprises: simulcasting the first downlink transmission over a
plurality of remote antenna units, wherein at least one of the
remote antenna units is positioned so that a coverage area
associated with the at least one remote antenna unit is not
adjacent to a coverage area associated with any of the other remote
antenna units of the plurality.
14. The RF connection matrix of claim 10, wherein routing the
second downlink transmission to one or more remote antenna units
comprises: simulcasting the second downlink transmission over a
plurality of remote antenna units, wherein at least one of the
remote antenna units is positioned so that a coverage area
associated with the at least one remote antenna unit is not
adjacent to a coverage area associated with any of the other remote
antenna units of the plurality.
15. A non-transitory machine-readable medium comprising
instructions operational on an RF connection matrix, which when
executed by a processor causes the processor to: receive a signal
associated with a sector identity (ID), the signal including a
first downlink transmission for transmission on a first carrier and
a second downlink transmission for transmission on a second
carrier; route the first downlink transmission to a first group of
two or more remote antenna units for simulcasting the first
downlink transmission on the first carrier over the first group of
two or more remote antenna units employing the sector identity
(ID); and route the second downlink transmission to a second group
of two or more remote antenna units for simulcasting the second
downlink transmission on the second carrier over the second group
of two or more remote antenna units employing the sector ID,
wherein at least one remote antenna unit of the second group
differs from the remote antenna units of the first group.
16. The non-transitory machine-readable medium of claim 15, further
comprising instructions operational on an RF connection matrix to
cause the processor to: convey the first downlink transmission for
the first carrier to a first carrier-specific RF connection matrix
module; and convey the second downlink transmission for the second
carrier to a second carrier-specific RF connection matrix
module.
17. The non-transitory machine-readable medium of claim 15, further
comprising instructions operational on an RF connection matrix to
cause the processor to: combine the first downlink transmission and
the second downlink transmission into a signal for at least
substantially simultaneous transmission by a remote antenna unit.
Description
TECHNICAL FIELD
Aspects of the present disclosure relate generally to wireless
communication systems, and more particularly, to simulcasting and
de-simulcasting of transmissions in wireless communication
systems.
BACKGROUND
In conventional wireless communication systems, base transceiver
stations (BTS or base station) facilitate wireless communication
between mobile units (e.g. access terminals) and an access network.
A typical base station includes multiple transceiver units and
antennas for sending radio signals to the mobile units (i.e.,
downlink transmissions) and for receiving radio signals from the
mobile units (i.e., uplink transmissions). Base stations are
typically located so as to strategically maximize communications
coverage over large geographical areas. Typically, the base
stations are communicatively coupled to the telephone network via
backhaul connections.
As requirements for the reliability and the throughput of wireless
communication systems continue to increase, solutions and methods
for providing high data rate cellular access with high
quality-of-service are desired. In some environments, a distributed
antenna system (DAS) may be employed, where instead of covering an
area by only one base station, the same coverage is provided by
multiple remote antenna units (RAU) controlled by a common base
station. In other words, a distributed antenna system (DAS) is a
network where spatially separated antenna nodes or remote antenna
units (RAUs) are connected to a common source via a transport
medium. A wireless communication system employing a distributed
antenna system (DAS) may thus provide improved wireless service
within a geographical area or structure. Some advantages of a
distributed antenna system (DAS) architecture configuration
include, for example, improved reliability, reduced total power,
possibility of increased capacity and more frequently occurring
line-of-sight (LOS) condition between the remote antenna units
(RAU) and the terminal device.
Although a distributed antenna system (DAS) architecture can
provide a number of benefits to a wireless communication system,
the full potential for such distributed antenna systems (DAS) can
be expanded by additional features.
SUMMARY
Various examples and implementations of the present disclosure may
relate to simulcasting and de-simulcasting in a distributed antenna
system (DAS) architecture for a wireless communication system.
According to one or more aspects of the disclosure, RF connection
matrices are provided for employments with a distributed antenna
system. In at least one example, an RF connection matrix may
include a first carrier-specific RF connection matrix module
adapted to route a first downlink transmission to one or more
remote antenna units for transmission on a first carrier. The RF
connection matrix may further include a second carrier-specific RF
connection matrix module adapted to route a second downlink
transmission to one or more remote antenna units for transmission
on a second carrier.
One or more further aspects of the disclosure provide methods
operational on an RF connection matrix and/or RF connection
matrices including means for performing such methods. According to
one or more examples of such methods, a signal associated with a
sector identity (ID) may be received, which signal may include a
first downlink transmission for transmission on a first carrier and
a second downlink transmission for transmission on a second
carrier. The first downlink transmission may be routed to one or
more remote antenna units for transmission on the first carrier,
and the second downlink transmission may be routed to one or more
remote antenna units for transmission on the second carrier.
Yet further aspects of the present disclosure provide
machine-readable mediums comprising instructions operational on an
RF connection matrix. According to one or more examples, such
instructions may cause a processor to receive a signal associated
with a sector identity (ID). The signal may include a first
downlink transmission for transmission on a first carrier and a
second downlink transmission for transmission on a second carrier.
The instructions may further cause the processor to route the first
downlink transmission to one or more remote antenna units for
transmission on the first carrier. The instructions may also cause
the processor to route the second downlink transmission to one or
more remote antenna units for transmission on the second
carrier.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram illustrating a network environment
according to at least one example in which one or more aspects of
the present disclosure may find application.
FIG. 2 is a block diagram illustrating at least one example of
staggered simulcasting distributions in a distributed antenna
system where each of three different carriers is configured with a
different simulcasting distribution.
FIG. 3 is a flow diagram illustrating at least one example of a
method for wireless communication.
FIG. 4 is a block diagram illustrating at least one example of a
distributed antenna system architecture employable in a geographic
area in which a population mass moves at least substantially as a
group.
FIG. 5 is a flow diagram illustrating at least one example of a
method for wireless communication.
FIG. 6 is a block diagram illustrating select components of a
network entity according to at least one example.
FIG. 7 is a simplified block diagram illustrating select components
of at least one example of a base station adapted to operate in
conjunction with an RF connection matrix for implementing one or
more of the features described herein for a distributed antenna
system (DAS).
FIG. 8 is a block diagram illustrating select details relating to
at least one example of the RF connection matrix of FIG. 7.
FIG. 9 is a block diagram illustrating select details relating to
at least one other example of an RF connection matrix of FIG.
7.
FIG. 10 is a flow diagram illustrating at least one example of a
method operational on an RF connection matrix.
FIG. 11 is a block diagram illustrating a base station including an
integrated base station simulcast controller module according to at
least one example.
FIG. 12 is a block diagram illustrating additional details relating
to the base station of FIG. 11, which includes the integrated base
station simulcast controller module according to at least one
example.
FIG. 13 is a flow diagram illustrating at least one example of a
method operational on a base station.
FIG. 14 is a block diagram illustrating select components of at
least one example of a distributed antenna system (DAS) employing a
base station simulcast controller module implemented as a
processing system adapted to communicate with a plurality of base
stations.
FIG. 15 is a flow diagram illustrating at least one example of a
method operational on a base station simulcast controller
module.
DETAILED DESCRIPTION
The following description set forth below in connection with the
appended drawings is intended as a description of various
configurations and is not intended to represent the only
configurations in which the concepts described herein may be
practiced. The following description includes specific details for
the purpose of providing a thorough understanding of various
concepts. However, it will be apparent to those skilled in the art
that these concepts may be practiced without these specific
details. In some instances, well known circuits, structures,
techniques and components are shown in block diagram form in order
to avoid obscuring such concepts.
In the following description, certain terminology is used to
describe certain features. For example, the term "base station" and
"access terminal" are used herein, and are meant to be interpreted
broadly. For example, a "base station" refers generally to a device
that facilitates wireless connectivity (e.g., for one or more
access terminals) to a communication or data network. A base
station may be capable of interfacing with one or more remote
antenna units. A base station may also be referred to by those
skilled in the art as an access point, a base transceiver stations
(BTS), a radio base station, a radio transceiver, a transceiver
function, a basic service set (BSS), an extended service set (ESS),
a Node B, an eNode B, a femto cell, a pico cell, or some other
suitable terminology.
An "access terminal" refers generally to one or more devices that
communicate with one or more other devices through wireless
signals. Examples of access terminals include mobile phones,
pagers, wireless modems, personal digital assistants, personal
information managers (PIMs), personal media players, palmtop
computers, laptop computers, tablet computers, televisions,
appliances, e-readers, digital video recorders (DVRs),
machine-to-machine (M2M) enabled devices, and/or other
communication/computing devices which communicate, at least
partially, through a wireless or cellular network.
FIG. 1 is a block diagram illustrating a network environment in
which one or more aspects of the present disclosure may find
application. The wireless communication system 100 is implemented
with a distributed antenna system (DAS) architecture and may be
configured according to one or more conventional telecommunication
system, network architecture, and/or communication standard. By way
of example and not limitation, the wireless communication system
100 may be configured according to one or more of Evolution Data
Optimized (EV-DO), Universal Mobile Telecommunication Systems
(UMTS), Long Term Evolution (LTE) (in FDD, TDD, or both modes),
LTE-Advanced (LTE-A) (in FDD, TDD, or both modes), CDMA2000, Ultra
Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX),
IEEE 802.20, Ultra-Wideband (UWB), Bluetooth, and/or other suitable
systems. The actual telecommunication system, network architecture,
and/or communication standard employed will depend on the specific
application and the overall design constraints imposed on the
system 100.
The wireless communication system 100 generally includes a
plurality of remote antenna units (RAUs) 102, one or more base
stations 104, a base station controller (BSC) 106, and a core
network 108 providing access to a public switched telephone network
(PSTN) (e.g., via a mobile switching center/visitor location
register (MSC/VLR)) and/or to an IP network (e.g., via a packet
data switching node (PDSN)). The system 100 can support operation
on multiple carriers (waveform signals of different frequencies).
Multi-carrier transmitters can transmit modulated signals
simultaneously on the multiple carriers. Each modulated signal may
be a CDMA signal, a TDMA signal, an OFDMA signal, a Single Carrier
Frequency Division Multiple Access (SC-FDMA) signal, etc. Each
modulated signal may be sent on a different carrier and may carry
control information (e.g., pilot signals), overhead information,
data, etc.
The remote antenna units 102, which are identified as 102-a, 102-b
and 102-c, are adapted to wirelessly communicate with one or more
access terminals 110. As illustrated, each of the remote antenna
units 102-a, 102-b, 102-c are spatially separated from each other
and are connected to a common base station 104 via a transport
medium 112. The transport medium 112 may include a fiber cable
and/or an optical cable in various examples. Accordingly, the base
station 104 can actively distribute signals to the plurality of
remote antenna units 102-a, 102-b, 102-c for communicating with the
one or more access terminals 110.
The base station 104 can be configured to communicate with the
access terminals 110 by means of the remote antenna units 102-a,
102-b, 102-c and under the control of the base station controller
106 via a plurality of carriers. The base station 104 can provide
communication coverage for a respective geographic area, referred
to herein as a cell. The cell can be divided into sectors 114
formed by the respective coverage area of each remote antenna unit
102-a, 102-b, 102-c, as shown by corresponding sectors 114-a, 114-b
and 114-c.
In at least some examples, a base station 104 can be adapted to
employ two or more of the remote antenna units 102-a, 102-b, 102-c
to transmit essentially the same signal, potentially to be received
at a single access terminal 110. This type of transmission is
typically referred to as simulcasting. For example, the base
station 104 may transmit a downlink signal from the two remote
antenna units 102-a and 102-b. Simulcasting can improve the signal
to interference and noise ratio (SINR) at the receiving access
terminal 110, since the signal from each remote antenna unit 102-a,
102-b ideally adds together constructively at the receiving access
terminal 110. Additionally, it is less likely that all the
simulcasted transmissions will be blocked due to geography or
fading than it might be for a transmission from a single remote
antenna unit 102. In the case where remote antenna units 102-a and
102-b simulcast a downlink signal, the two areas depicted by
sectors 114-a and 114-b can become a single sector and may employ a
single sector identity (e.g., a single pseudo-random noise (PN)
code).
The base station 104 can also be adapted to transmit different
signals from different remote antenna units 102-a, 102-b, 102-c.
This type of transmission is typically referred to as
de-simulcasting. For example, the base station 104 may be adapted
to transmit a different downlink signal from the remote antenna
unit 102-c. De-simulcasting can be performed using the same carrier
frequency as the one used by the other remote antenna units 102-a,
102-b, or using a different carrier frequency. De-simulcasting can
improve the capacity of the wireless communication system 100 by
increasing the data rate per unit area. That is, when each remote
antenna unit 102-a, 102-b, 102-c serving a particular geographic
area is transmitting a different signal, a greater number of access
terminals 110 may be served by the system 100. In the case where a
remote antenna unit 102-a, 102-b, 102-c is adapted to de-simulcast
downlink signals, each area 114-a, 114-b, 114-c employs an
individual and separate sector ID.
As noted above, a plurality of remote antenna units can be adapted
to simulcast downlink transmissions, where each group of
simulcasting remote antenna units forms a sector. As used herein, a
plurality of simulcasting remote antenna units can form a sector by
employing a common sector identity, such as a common pseudo-random
noise (PN) code. FIG. 2 is a block diagram illustrating a coverage
area 200 including a plurality of remote antenna units (such as the
remote antenna units 102-a, 102-b, 102-c of FIG. 1) acting in
groups to simulcast downlink transmissions. As depicted, each
hexagon represents a coverage area associated with one remote
antenna unit for transmitting and receiving radio signals. In
addition, each remote antenna unit (i.e., each hexagon) is
associated with one or more other remote antenna units (i.e., one
or more other hexagons) forming a group for simulcasting downlink
transmissions. Each simulcasting group of two or more remote
antenna units can employ a common sector ID to form a single
sector. In the examples depicted by FIG. 2, the coverage area 200
is configured with nineteen (19) different simulcasting groups
(e.g., sectors A through S each depicted with unique hatch
patterns), where each simulcasting group includes three (3) remote
antenna units.
According to a feature of the present disclosure, the coverage area
200 can be configured to employ different simulcasting group
configurations for each of a plurality of different carriers (e.g.,
different waveform signals of different frequencies). In other
words, the remote antenna units employed for simulcasting downlink
transmissions with a particular sector ID for a first carrier can
differ from the remote antenna units employed for simulcasting
downlink transmissions with the same sector ID for a second
carrier. This feature can be further understood by reference to the
non-limiting example depicted by the three different diagrams shown
in FIG. 2.
The top diagram in FIG. 2 shows the simulcasting group distribution
for a first carrier in the coverage area 200. As illustrated, the
remote antenna units are grouped into nineteen (19) different
simulcasting groups, where each group employs a different sector ID
(e.g., sector IDs A-S). Each group includes three (3) different
remote antenna units, and simulcasts downlink transmissions for the
first carrier using a common sector ID. For example, the remote
antenna units forming the group adapted to simulcast downlink
transmissions with the sector ID `A` for the first carrier are
shown to include the middle three (3) remote antenna units depicted
without any hatch pattern and indicated by arrow 202. Similarly,
the remote antenna units forming the group adapted to simulcast
downlink transmission with the sector ID `P` for the first carrier
are shown to include the three (3) remote antenna units located at
the top and middle of the coverage area 200, and are depicted with
a hatch pattern of vertical lines and indicated by arrow 204.
In the middle diagram of FIG. 2, the simulcasting group
distribution for a second carrier is shown for the same coverage
area 200. In this example, the same nineteen (19) different sector
IDs are employed (e.g., sector IDs A-S). However, for the second
carrier, each simulcasting group (e.g., each sector ID) employs a
different group of three (3) remote antenna units for simulcasting
downlink transmissions. For instance, in the example depicted by
FIG. 2, the remote antenna units forming the group adapted to
simulcast downlink transmissions with the sector ID `A` (indicated
by arrow 206) for the second carrier are shown to include two (2)
remote antenna units that differ from the remote antenna units
employed for simulcasting with the same sector ID `A` for the first
carrier. In this example, each of the simulcasting groups is
shifted up and to the right.
For some simulcasting groups with the second carrier, the remote
antenna units are separated so that the three (3) remote antenna
units of a simulcasting group are no longer adjacent to one another
like they were for the first carrier. For instance, the group of
remote antenna units employed for simulcasting downlink
transmissions with the sector ID `P` for the second carrier are
shown to include one (1) remote antenna unit 208 at the top and
middle of the coverage area 200, and two (2) other remote antenna
units 210 at the bottom left side of the coverage area 200.
The bottom diagram of FIG. 2 illustrates the simulcasting group
distribution for a third carrier for the same coverage area 200. In
this example, the same nineteen (19) different sector IDs are
employed (e.g., sector IDs A-S). However, for the third carrier,
each simulcasting group (e.g., each sector ID) employs yet another
different group of three (3) remote antenna units for simulcasting
downlink transmissions. For instance, in the example depicted by
FIG. 2, the remote antenna units forming the group adapted to
simulcast downlink transmissions with the sector ID `A` (indicated
by arrow 212) for the third carrier are shown to include two (2)
remote antenna units that differ from the remote antenna units
employed for simulcasting with the same sector ID for the first or
second carriers. In this example, each of the simulcasting groups
is shifted up and to the left.
As with the middle diagram, the bottom diagram includes some
simulcasting groups including remote antenna units that are
spatially separated and no longer adjacent to one another. For
example, the group of remote antenna units employed for
simulcasting downlink transmissions with the sector ID `P` for the
third carrier are shown to include one (1) remote antenna unit 214
at the top and center of the coverage area 200, one (1) remote
antenna unit 216 at the lower left side of the coverage area 200,
and one (1) remote antenna unit 218 at the lower right side of the
coverage area 200.
In the illustrated example, where the simulcasting configurations
have a 3:1 ratio (i.e., three (3) remote antenna units to one (1)
sector), a significant improvement in the signal to interference
and noise ratio (SINR) can be achieved by providing different
simulcasting group distributions for different carriers. For
instance, a conventional distributed antenna system (DAS) would
employ only one of the three simulcasting group distribution
configurations of FIG. 2 for all three carriers. That is, a
conventional distributed antenna system (DAS) would typically use
either the top, middle or bottom configuration for all three
carriers, and would achieve some improvement to signal to
interference and noise ratio (SINR) for access terminals
distributed through the coverage area 200. By comparison, employing
the simulcasting architecture where a different simulcasting group
distribution is employed for each carrier according to the
configurations described above, the signal to interference and
noise ratio (SINR) can be further improved. By way of example and
not limitation, a four (4) dB improvement was determined in the
described configurations in the 10% tail for single-carrier access
terminals which are uniformly dropped over the geography, when they
are assigned to the carrier which has the best simulcasting pattern
for the particular location of the access terminal.
In addition, an overall gain in network throughput can also be
obtained by employing the three different simulcasting group
distributions of FIG. 2 as compared to employing the same
simulcasting group distribution for all carriers. In the described
configurations, more time can be allocated on the simulcasting
distribution which is best for each user, resulting in an overall
gain in the network throughput as well as an increase in the 10%
tail throughput. By way of example and not limitation, an increase
in the overall network throughput as well as an increase in the 10%
tail throughput of 27% was determined in the particular example
shown in FIG. 2. However, smaller or larger throughput gains may be
possible, depending on the specific deployment model
implemented.
It is noted that the number of carriers and the simulcasting
distribution configurations described above with reference to FIG.
2 are only examples, and that other configurations and other
numbers of carriers may be employed according to various
implementations of the underlying features.
At least one aspect of the present disclosure includes methods for
wireless communication. FIG. 3 is a flow diagram illustrating at
least one example of a method 300 for wireless communication
associated with the features described above with reference to FIG.
2. The method 300 includes simulcasting downlink transmissions on a
first carrier with a first group of two or more remote antenna
units employing a common sector ID at step 302. At step 304,
downlink transmissions are simulcast on a second carrier with a
second group of two or more remote antenna units employing the same
sector ID. At least one remote antenna unit of the second group
differs from the remote antenna units making up the first
group.
For example, the group 202 in FIG. 2 may be a first group of remote
antenna units simulcasting downlink transmissions with the sector
ID `A` on the first carrier, and the group 206 may be the second
group of remote antenna units simulcasting downlink transmission
with the same sector ID `A` on the second carrier. In the example,
the remote antenna units making up the group 202 are different from
the remote antenna units making up the group 206. That is, two of
the remote antenna units of the second group 206 are different
remote antenna units from the remote antenna units making up the
first group 202. In this non-limiting example, one of the remote
antenna units in the first group 202 is also included as a remote
antenna unit of the second group 206.
At least some features of the present disclosure relate to
increasing efficiency by strategically distributing resources in a
coverage area. Typically, strategies for increasing the spectral
efficiency for a particular area have included increasing the
number of base station sectors in that area by an increase in the
number of base stations, which base stations can be fairly
expensive. In some instances, however, all locations within the
particular coverage area may not need increased spectral efficiency
at the same time. It has been determined that masses of people may
tend to move together, so that increased spectral efficiency would
be beneficial at only one portion of a given area for each moment
in time. For example, FIG. 4 is a block diagram illustrating a
geographic coverage area 400 where a majority of the population may
be found in and around the area 402 during one part of each day
and/or week, and in and around the area 404 during another part of
each day and/or week. For instance, a majority of the population
within the coverage area 400 may move into the area 402 in the
mornings as the population goes to work, and then may be found
generally in the area 404 in the evenings as the population returns
to their homes.
According to a feature, simulcasting distribution configurations
may be implemented for increased efficiency in distributing
resources within a coverage area. For instance, a simulcasting
distribution configuration may be implemented in a manner to
increase spectral efficiency by increasing the number of sectors in
a given part of the coverage area, without increasing the number of
base stations.
Referring still to FIG. 4, a plurality of remote antenna units 102
are spatially distributed throughout the coverage area 400. In the
illustrated example, simulcasting groups are formed with remote
antenna units that are geographically separated such that the
respective coverage areas of the remote antenna units forming a
simulcasting group are generally not adjacent to one another. In
general, the geographic separation between simulcasting remote
antenna units may be such that an access terminal communicating
with at least one remote antenna unit of a simulcasting group is
not able communicate with at least one other remote antenna unit of
the same simulcasting group at any given time.
Each simulcasting group is depicted in FIG. 4 with a letter
indicating a sector ID with which the remote antenna units are
configured to simulcast downlink transmissions. For example, the
two remote antenna units 102A are depicted with the letter `A` to
indicate that these two remote antenna units are adapted to
simulcast transmissions using the same sector ID `A`. Similarly,
the two remote antenna units 102E are depicted with the letter `E`
to indicate that these two remote antenna units simulcast
transmissions using the same sector ID `E`. As shown, the two
remote antenna units 102A are geographically separated such that
the respective coverage areas of each remote antenna unit 102A are
not adjacent. The two remote antenna units 102E are likewise
geographically separated. Similar simulcasting pairs are also shown
for sector IDs `B` through `D` and `F` through `I`, with the remote
antenna units for each pair being geographically separated from one
another.
In the illustrated example, wherever there is a mass of users
concentrated in a given area (e.g., 402 or 404), those users are
served by multiple sectors. For instance, when a large majority of
the population is found in and around the area 402 (e.g., in the
morning), they will be served generally by all of the sectors
`A`-`I`. When the majority of the population moves to an area in
and around the area 404 (e.g., in the evening), they will be served
generally by the same number of sectors `A`-`I`. As the population
moves throughout the network in a large majority, there is a low
probability all remote antenna units will experience large
throughput demands. Therefore, with the simulcasting pattern shown
in FIG. 4, the population mass will typically be served by eight
(8) or nine (9) different sectors as the population moves at least
substantially together throughout the network. This is about twice
as many sectors as would be available in a typical configuration
where simulcasting remote antenna units would be geographically
adjacent to one another. In addition, the number of sectors per
area is increased without increasing the number of base stations
serving that area. Furthermore, if the same population becomes less
concentrated and spreads more evenly throughout the coverage area
400, the sectors `A`-`I` employed for serving the entire coverage
area 400 across the distributed simulcasting pattern of remote
antenna units 102 is still sufficient to meet the population's
demand.
It is noted that in some implementations not all the remote antenna
units within a particular coverage area 400 may be adapted to
simulcast. Instead, there may be a combination of simulcasting
remote antenna units and de-simulcasting remote antenna units,
according to numerous possible configurations.
At least one aspect of the present disclosure includes methods for
wireless communication. FIG. 5 is a flow diagram illustrating at
least one example of a method 500 for wireless communication
associated with the features described above with reference to FIG.
4. The method 500 includes simulcasting downlink transmissions with
a first remote antenna unit at step 502. At step 504, the downlink
transmissions are also simulcast with a second remote antenna unit,
such that the first remote antenna unit and the second remote
antenna unit form a simulcasting group. The second remote antenna
unit is located so that a coverage area associated with the second
remote antenna unit is not adjacent to a coverage area associated
with the first remote antenna unit.
For example, the plurality of remote antenna units identified by
reference number 102A in FIG. 4 may simulcast downlink
transmissions. As depicted, the coverage area (depicted by each
respective hexagon) of the two remote antenna units 102A are not
adjacent to each other.
According to at least one feature, the simulcasting distribution
configurations and associated methods for wireless communications
described above with reference to FIGS. 2-5 may be dynamically
configured. In some instances, the network (e.g., a base station, a
base station controller, etc.) can measure one or more parameters
(e.g., the interference, traffic demand statistics, etc.) and
determine how to arrange the simulcasting group configurations
across the geography and across carriers to increase stability and
throughput to each user, as well as to the network as a whole. For
example, at least one remote antenna unit in a simulcasting group
can be changed in response to one or more network traffic
parameters. That is, one or more remote antenna units can be added
to and/or removed from a simulcasting group in response to at least
one network traffic parameter.
For instance, it may occur that access terminals operating within a
coverage area are not dispersed uniformly through the area. For
example, it may be determined by the network that access terminals
in a specific region are especially active at a particular time
along one or more handoff boundaries (e.g., along a region between
simulcasting groups `C` and `P` in the top diagram of FIG. 2). In
such an instance, it may be beneficial to dynamically change the
simulcasting group distributions. For example, the simulcasting
group distributions may be dynamically modified by the network to
employ a simulcasting group distribution that optimizes the
throughput and capacity for those access terminals. In the example
from FIG. 2, for instance, it may be beneficial to dynamically
change the group distributions so that two of the carriers or even
all three carriers employ the same simulcasting group distribution
determined to optimize the throughput and capacity for those access
terminals located along the one or more handoff boundaries
indicated above. That is, the network may change at least one
remote antenna unit in any of the different groups for any of the
different carrier configurations. When the network dynamics return
to a more uniformly dispersed access terminal distribution, the
simulcasting distribution configuration can return to the three
configurations depicted in FIG. 2, or some other
configurations.
In the example of FIG. 4, the network may be adapted to identify
the movement of the mobile population and responsively adapt the
simulcasting group configurations to accommodate the population
mass. For instance, the network may identify a large concentration
of access terminals in a particular area. For example, there may be
a sporting contest, concert, or other spectacle scheduled at a
specific venue, causing the population to move generally together
as a group and concentrate in and around that venue. The network
may identify this movement in the population and may deploy a
simulcasting group configuration similar to the configuration
depicted by FIG. 4 in order to increase a number of sectors
available for the area around the venue in order to improve network
performance for the concentrated population. That is, the network
can change which remote antenna units simulcast by, for example,
adding one or more remote antenna units to and/or removing one or
more remote antenna units from a simulcasting group in response to
at least one network traffic parameter.
The various features, simulcasting configurations and methods for
wireless communication described above can be implemented by one or
more network entities. Such one or more network entities may be
generally implemented with one or more processing systems. FIG. 6
is a block diagram illustrating select components of a processing
system 600 according to at least one example. The processing system
600 may generally include a processing circuit 602 coupled to a
communications interface 604 and to a storage medium 606. In at
least some examples, the processing circuit 602 may be coupled to
the communications interface 604 and the storage medium 606 with a
bus architecture, represented generally by the bus 608. The bus 608
may also link various other circuits such as timing sources,
peripherals, voltage regulators, and power management circuits,
which are well known in the art, and therefore, will not be
described any further.
The processing circuit 602 is arranged to obtain, process, and/or
send data, control data access and storage, issue commands, and
control other desired operations. The processing circuit 602 may
include circuitry configured to implement desired programming
provided by appropriate media in at least one embodiment. For
example, the processing circuit 602 may be implemented as one or
more of a processor, a controller, a plurality of processors and/or
other structure configured to execute executable instructions
including, for example, software and/or firmware instructions,
and/or hardware circuitry. Examples of the processing circuit 602
may include a general purpose processor, a digital signal processor
(DSP), an application specific integrated circuit (ASIC), a field
programmable gate array (FPGA) or other programmable logic
component, discrete gate or transistor logic, discrete hardware
components, or any combination thereof designed to perform the
functions described herein. A general purpose processor may be a
microprocessor but, in the alternative, the processor may be any
conventional processor, controller, microcontroller, or state
machine. A processor may also be implemented as a combination of
computing components, such as a combination of a DSP and a
microprocessor, a number of microprocessors, one or more
microprocessors in conjunction with a DSP core, or any other such
configuration. These examples of the processing circuit 602 are for
illustration and other suitable configurations within the scope of
the present disclosure are also contemplated.
The processing circuit 602 is adapted for processing, including the
execution of programming, which may be stored on the storage medium
606. As used herein, the term "programming" shall be construed
broadly to include without limitation instructions, instruction
sets, code, code segments, program code, programs, subprograms,
software modules, applications, software applications, software
packages, routines, subroutines, objects, executables, threads of
execution, procedures, functions, etc., whether referred to as
software, firmware, middleware, microcode, hardware description
language, or otherwise.
The communications interface 604 is configured to facilitate wired
and/or wireless communications of the processing system 600. For
example, the communications interface 604 may include circuitry
and/or programming adapted to facilitate the communication of
information bi-directionally with respect to one or more other
processing systems. In instances where the communications interface
604 is configured to facilitate wireless communications, the
communications interface 604 may be coupled to one or more antennas
(not shown), and may includes wireless transceiver circuitry,
including at least one receiver circuit 610 (e.g., one or more
receiver chains) and/or at least one transmitter circuit 612 (e.g.,
one or more transmitter chains).
The storage medium 606 may represent one or more devices for
storing programming and/or data, such as processor executable code
or instructions (e.g., software, firmware), electronic data,
databases, or other digital information. The storage medium 606 may
also be used for storing data that is manipulated by the processing
circuit 602 when executing programming. The storage medium 606 may
be any available media that can be accessed by a general purpose or
special purpose processor. By way of example and not limitation,
the storage medium 606 may include a non-transitory
computer-readable medium such as a magnetic storage device (e.g.,
hard disk, floppy disk, magnetic strip), an optical storage medium
(e.g., compact disk (CD), digital versatile disk (DVD)), a smart
card, a flash memory device (e.g., card, stick, key drive), random
access memory (RAM), read only memory (ROM), programmable ROM
(PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM),
a register, a removable disk, and/or other non-transitory
computer-readable mediums for storing information, as well as any
combination thereof. The storage medium 606 may be coupled to, or
at least accessible by the processing circuit 602 such that the
processing circuit 602 can read information from, and write
information to, the storage medium 606. For instance, the storage
medium 606 may be resident in the processing system 600, external
to the processing system 600, or distributed across multiple
entities including the processing system 600. In some examples, the
storage medium 606 may be integral to the processing circuit
602.
Programming stored by the storage medium 606, when executed by the
processing circuit 602, causes the processing circuit 602 to
perform one or more of the various functions and/or process steps
described herein. The storage medium 606 may include simulcasting
group distribution operations (i.e., instructions) 614. The
simulcasting group distribution operations 614 can be implemented
by the processing circuit 602. Thus, according to one or more
aspects of the present disclosure, the processing circuit 602 may
be adapted to perform any or all of the processes, functions, steps
and/or routines for any or all of the network entities (e.g., base
station 104, 702, 1102; base station controller 106, 708, 1106; RF
connection matrix 704; base station simulcast controller module
1114, 1402 etc.) described herein. As used herein, the term
"adapted" in relation to the processing circuit 602 may refer to
the processing circuit 602 being one or more of configured,
employed, implemented, or programmed to perform a particular
process, function, step and/or routine according to various
features described herein.
In at least one example, a processing system 600 may be implemented
as an RF connection matrix, which may also be referred to as a
"head end", and/or as a base station coupled with such an RF
connection matrix. Such a processing system 600 can be adapted to
facilitate simulcasting according to one or more of the features
described herein, such as those described above with reference to
FIGS. 2-5. FIG. 7 is a simplified block diagram illustrating select
components of a base station 702 adapted to operate in conjunction
with an RF connection matrix 704 for implementing one or more of
the features described herein for a distributed antenna system
(DAS).
As shown, a base station (BS) 702 is utilized to enable multiple
access wireless communication. The base station 702 includes a
backhaul interface 706 for backhaul communication with a base
station controller (BSC) 708. Further, the base station 702
includes a base station modem block 710 including a plurality of
base station sector controllers 712A, 712B, and 712C, and a
corresponding plurality of base station antenna ports 714A, 714B,
and 714C. Within the base station modem block 710, the respective
base station sector controllers 712A, 712B, and 712C each include
circuitry for transmitting a downlink and receiving an uplink for
one sector or cell in the wireless communication system. In one
example, all of the base station sector controllers 712A, 712B, and
712C may reside on the same channel card. In another example, they
may be on different channel cards. The base station antenna ports
714A, 714B, and 714C are each coupled to an RF connection matrix
704.
In this example, the RF connection matrix 704 determines how the
outgoing signals are routed from the base station 702 to a
plurality of remote antenna units 716 for downlink transmission.
Typically, the coupling between the base station antenna ports 714
and the RF connection matrix 704 is made by way of respective RF
electrical communication interfaces. The RF connection matrix 704
is coupled to a plurality of remote antenna units 716 (e.g., 716A,
716B, 716C, 716D, and 716E). In at least some implementations, the
coupling between the RF connection matrix 704 and the remote
antenna units 716 includes respective transport medium interfaces
718A, 718B, 718C, 718D, and 718E. Each of the base station antenna
ports 714A, 714B, 714C may include one or more antenna ports to
facilitate coupling a respective base station sector with one
remote antenna unit 716 or with a plurality of remote antenna units
716.
The distributed antenna system (DAS) illustrated in FIG. 7 may be
utilized for simulcasting and de-simulcasting any of a plurality of
configurations including configurations according to the general
principles described above. For example, the remote antenna units
716A and 716B may be simulcast, the remote antenna units 716C and
716D may be simulcast, and the remote antenna unit 716E may be
de-simulcast. Furthermore, the depicted grouping can be implemented
for one carrier, while other carriers may employ different grouping
configurations.
The RF connection matrix 704 may employ various configurations,
such as one of the configurations depicted in FIGS. 8 and 9.
Referring initially to FIG. 8, a block diagram is shown
illustrating select details relating to at least one example of an
RF connection matrix. The example depicted in FIG. 8 can be
employed for various simulcasting configurations where a plurality
of remote antenna units 716 are employed for simulcasting downlink
transmissions. By way of example and not limitation, the RF
connection matrix 704A may be employed for implementing one or more
of the features described herein with reference to FIG. 4.
In FIG. 8, the three base station sector controllers 712A, 712B,
and 712C are shown. Here, the base station sector controllers 712A,
712B, and 712C are coupled, by way of a backhaul connection 706, to
the base station controller 708. Further, the base station
controller 708 is coupled to a network such as the Internet 802.
Although the base station antenna ports 714 are not illustrated in
FIG. 8, the interface between the base station sector controllers
712A, 712B, and 712C and the RF connection matrix 704A is assumed
to include such antenna ports.
The RF connection matrix 704A is provisioned to route the outgoing
signals from the base station sectors 712A, 712B, 712C to the
remote antenna units 716 for downlink transmission. Here, the RF
connection matrix 704A includes an electrical portion where
electrical RF signals output by the base station sectors 712 are
provided to a central hub 804 having optical-electrical interfaces
(O/E) for coupling the electrical RF signals with optical fibers
806 for transmission to the remote antenna units 716 as optical
signals in an optical portion. The optical signals are then
converted back to electrical signals at electrical-optical
interfaces (E/O) 808 for interfacing directly with antennas. Here,
the E/O and various active elements are illustrated at the remote
antenna units 716. However, in various examples all or some portion
of these components may be located outside the remote antenna units
716.
In the illustrated example, the RF connection matrix 704A is
provisioned to simulcast the downlink signal from the first base
station sector 712A from the first two remote antenna units 716A
and 716B. As an example, simulcasting can be accomplished by way of
RF combining in the electrical portion of the RF connection matrix
704A, as depicted at 810. That is, the electrical signal
representing a downlink transmission sent from the first base
station sector 712A is split and fed to two O/E interfaces at the
central hub 804, so that corresponding optical signals are
transmitted over the first and second fibers 806A and 806B to the
first and second remote antenna units 716A and 716B to be
simulcasted.
Further, the RF connection matrix 704A is provisioned to simulcast
the downlink signal from the second base station sector 712B from
the third and fourth remote antenna units 716C and 716D. As another
example, simulcasting can be accomplished by way of fiber combining
in the optical portion of the RF connection matrix 704A, as
depicted at 806C. That is, the electrical signal representing a
downlink transmission sent from the second base station sector 712B
is fed into an O/E interface at the central hub 804, after which
the corresponding optical signal is split from one to two fibers
806C, so that the corresponding optical signals are sent to the
third and fourth remote antenna units 716C and 716D to be
simulcasted.
Still further, the RF connection matrix 704A is provisioned to
de-simulcast the downlink signal from the third base station sector
712C from the fifth remote antenna unit 716E. That is, the
electrical signal representing a downlink transmission sent from
the third base station sector 712C is fed into an O/E interface at
the central hub 804, after which the corresponding optical signal
is sent to the fifth remote antenna unit 716E to be
transmitted.
Turning to FIG. 9, a block diagram is shown illustrating select
details relating to at least one other example of an RF connection
matrix. The example depicted in FIG. 9 can be employed for various
simulcasting configurations where a plurality of remote antenna
units 716 are employed for simulcasting downlink transmissions, as
well as for implementing different simulcasting configurations
among two or more different carriers. By way of example and not
limitation, an RF connection matrix 704B depicted in FIG. 9 may be
employed for implementing one or more of the features described
above with reference to FIGS. 2 and 4.
In FIG. 9, the three base station sector controllers 712A, 712B,
and 712C are once again depicted with the base station sector
controllers 712A, 712B, and 712C coupled by way of a backhaul
connection 706 to the base station controller 708. Further, the
base station controller 708 is coupled to a network such as the
Internet 902. Although the base station antenna ports 714 from FIG.
7 are not illustrated in FIG. 9, the interface between the base
station sector controllers 712A, 712B, and 712C and the RF
connection matrix 704B (e.g., the carrier separation filters 904)
is assumed to include such base station antenna ports 714 in FIG.
7.
The RF connection matrix 704B is provisioned to route the outgoing
signals from the base station sector controllers 712A, 712B, 712C
to the remote antenna units 716 for downlink transmission. In the
example of FIG. 9, the RF connection matrix 704B includes a
plurality of carrier-specific RF connection matrix modules 906.
Each of the respective carrier-specific RF connection matrix
modules 906 can route the carrier-specific downlink transmissions
to one or more remote antenna units 716 for transmission on the
respective carrier.
The RF connection matrix 704B can include a carrier separation
filter 904 coupled with the antenna ports for each base station
sector controller 712. For instance, respective carrier separation
filters 904A, 904B, and 904C are coupled with the base station
sector controllers 712A, 712B, and 712C. Each of the carrier
separation filters is further coupled with the plurality of
carrier-specific RF connection matrix modules 906. The carrier
separation filters 904 are adapted to receive one or more signals
associated with a sector identity (ID), where the one or more
signals include downlink transmissions for a plurality of carriers.
For instance, a carrier separation filter 904 may receive one or
more signals from one or more base station sector controllers 712.
The carrier separation filters 904 then separate the downlink
transmissions for each carrier and provide these downlink
transmissions to a respective carrier-specific RF connection matrix
module 906.
In some examples, the carrier-specific RF connection matrix modules
906 may provide the carrier-specific downlink transmissions to a
carrier combine filter 908 associated with a respective remote
antenna unit 716. For instance, the carrier combine filters 908A,
908B, and 908C are respectively associated with remote antenna
units 716A, 716B, and 716C. The carrier combine filters 908 can
receive from each of the carrier-specific RF connection matrix
modules 906 the downlink transmissions intended for the associated
remote antenna units 716, and can combine the various signals for
transmission to respective remote antenna units 716.
Although there is an equal number of base station sector
controllers 712 and remote antenna units 716, it will be apparent
to a person of ordinary skill in the art that the number of remote
antenna units 716 may be different from the number of base station
sector controllers 712, and the specific number of base station
sector controllers 712 and remote antenna units 716 can vary
according various implementations.
By way of an example and not by way of limitation, the base station
sector controller 712A may convey to the carrier separation filter
904A a signal including downlink transmissions for a first carrier
(e.g., carrier 1) and for a second carrier (e.g., carrier 2). These
downlink transmissions are associated with a common sector identity
(ID) of the base station sector controller 712A. The carrier
separation filter 904A filters the signal to convey the downlink
transmission for the first carrier to the carrier-specific RF
connection matrix module 906 for carrier 1 and the downlink
transmission for the second carrier to the carrier-specific RF
connection matrix module 906 for carrier 2.
Generally speaking, and by way of example only, the carrier
separation filter 904A may receive a signal from the base station
sector controller 712A that includes downlink transmissions for a
first carrier and downlink transmissions for a second carrier. The
carrier separation filter 904A may filter the downlink
transmissions communicated to the carrier-specific RF connection
matrix module 906 for carrier 1 to include only those downlink
transmissions for the first carrier. Similarly, the carrier
separation filter 904A may filter the downlink transmissions
communicated to the carrier-specific RF connection matrix module
906 for carrier 2 to include only those downlink transmissions for
the second carrier. Similar operations may occur in the other base
station sector controllers 712B and 712C, and in the carrier
separation filters 904B and 904C.
The carrier-specific RF connection matrix module 906 for carrier 1
can route received downlink transmissions to one or more remote
antenna units 716 for transmission on the first carrier. Similarly,
the carrier-specific RF connection matrix module 906 for carrier 2
can route received downlink transmissions to one or more remote
antenna units 716 for transmission on the second carrier.
Simulcasting can be accomplished by way of RF combining in the
carrier-specific RF connection matrix modules 906 in a manner
similar to the RF combining described above with reference to the
electrical portion of the RF connection matrix 704A in FIG. 8.
With the downlink transmissions in the respective carrier-specific
RF connection matrix modules 906 directed to their intended remote
antenna units 716, the downlink transmission signals from a
plurality of the carrier-specific RF connection matrix modules 906
can be combined for downlink transmissions in the carrier combine
filters 908 associated with each respective remote antenna unit
716. The combined signals can be fed to the O/E interfaces so that
corresponding optical signals are transmitted over the respective
optical cables 910 to the antenna units 716 for de-simulcast and/or
simulcast transmissions.
As depicted in FIG. 9, the RF connection matrix 704B can facilitate
different simulcast grouping per carrier by decomposing
multicarrier base station signals into separate per-carrier signals
in the carrier separation filters 904, and employing
carrier-specific RF connection matrix modules 906 for each carrier.
Moreover, in addition to facilitating different simulcast groupings
per carrier, the RF connection matrix 704B can also facilitate
simulcasting on the downlink while using diversity antennas on the
uplink. From a capacity standpoint, it can be beneficial to exploit
available diversity on the uplink, and the presented RF connection
matrix 704B can provide increased uplink capacity compared to
conventional RF connection matrix configurations, which typically
simulcast on the uplink. The separation of downlink and uplink
multiplexing is not explicitly shown in FIG. 9, but will be readily
understood from the diagram by a person of ordinary skill in the
art.
Turning to FIG. 10, a flow diagram is shown illustrating at least
one example of a method operational on an RF connection matrix,
such as the RF connection matrix 704B. Notably, although the
following example only refers to two different sector IDs and only
two different carriers, it should be understood that the specific
number of sector IDs and/or carriers can vary across any of a
plurality of different examples. With reference to FIGS. 9 and 10,
a signal can be received at step 1002, where the signal is
associated with a sector ID and includes downlink transmissions for
a plurality of carriers. For example, the RF connection matrix 704B
may receive one or more signals from a base station sector
controller 712, where the received signal is associated with a
sector ID. For instance, the RF connection matrix 704B may receive
a signal from the base station sector controller 712A associated
with a first sector ID, and a signal from the base station sector
controller 712B associated with a second sector ID. The received
signal(s) (e.g., from each base station sector controller 712) may
include one or more downlink transmissions for transmission on a
first carrier and one or more downlink transmissions for
transmission on a second carrier. The signal(s) from each base
station sector controller 712 may be received at a respective
carrier separation filter 904.
At step 1004, downlink transmissions for a first carrier can be
conveyed to a first carrier-specific RF connection matrix module
906. For example, the carrier separation filters 904 can filter out
downlink transmissions for any carriers other than the first
carrier, and can convey the resulting downlink transmissions for
the first carrier to the carrier-specific RF connection matrix
module 906 for the first carrier. The carrier-specific RF
connection matrix module 906 for the first carrier can accordingly
receive downlink transmissions for one or more sector IDs
associated with the first carrier.
Similarly, at step 1006, downlink transmissions for a second
carrier can be conveyed to a second carrier-specific RF connection
matrix module 906. For example, the carrier separation filters 904
can filter out downlink transmissions for any carriers other than
the second carrier, and can convey the resulting downlink
transmissions for the second carrier to the carrier-specific RF
connection matrix module 906 for the second carrier. The
carrier-specific RF connection matrix module 906 for the second
carrier can accordingly receive downlink transmissions for one or
more sector IDs associated with the second carrier.
At step 1008, the first carrier-specific RF connection matrix
module 906 can route the downlink transmissions for the first
carrier to one or more remote antenna units for transmission on the
first carrier. For example, the carrier-specific RF connection
matrix module 906 for the first carrier can route the downlink
transmissions associated with each sector ID for the first carrier
to one or more remote antenna units 716. Routing for facilitating
simulcasting by two or more remote antenna units 716 can be
accomplished by way of RF combining in a manner similar to the RF
combining in the electrical portion of the RF connection matrix, as
described above relating to the RF connection matrix 704A in FIG.
8.
Similarly, at step 1010, the second carrier-specific RF connection
matrix module 906 can route the downlink transmissions for the
second carrier to one or more remote antenna units for transmission
on the second carrier. For example, the carrier-specific RF
connection matrix module 906 for the second carrier can route the
downlink transmissions for the second carrier to one or more remote
antenna units 716. Routing for facilitating simulcasting by two or
more remote antenna units 716 can be accomplished by way of RF
combining in a manner similar to the RF combining in the electrical
portion of the RF connection matrix, as described above relating to
the RF connection matrix 704A in FIG. 8.
In at least some examples where both the first and second
carrier-specific RF connection matrix modules 906 may route
downlink transmissions to one or more of the same remote antenna
units 716. In such an example, the signals received from the two
carrier-specific RF connection matrix modules 906 can be combined
into a signal by a carrier combine filter 908 prior to transmission
by the respective remote antenna units 716.
According to the forgoing examples, the RF connection matrix 704B
can implement one or more of the features described herein above
with reference to FIGS. 2-5. For example, the carrier-specific RF
connection matrix module 906 for the first carrier can simulcast a
downlink transmission on the first carrier over a first group of
two or more remote antenna units 716 employing a particular sector
ID. Furthermore, the carrier-specific RF connection matrix module
906 for the second carrier can simulcast a downlink transmission on
the second carrier over a second group of two or more remote
antenna units employing the sector ID, wherein at least one remote
antenna unit of the second group differs from the remote antenna
units of the first group. In another example, the carrier-specific
RF connection matrix modules 906 can simulcast downlink
transmissions over a plurality of remote antenna units 716, where
at least one of the remote antenna units 716 is positioned so that
a coverage area associated with the at least one remote antenna
unit is not adjacent to a coverage area associated with any of the
other remote antenna units of the plurality.
Referring back to FIG. 7, in order to adapt the RF connection
matrix 704 (e.g., RF connection matrix 704A in FIG. 8 and/or RF
connection matrix 704B in FIG. 9) to perform one or more of the
features described herein with reference to FIGS. 2 and 4, the
provisioning for a particular simulcasting configuration can be
highly complex, involving appropriate electrical and/or optical
connections to provide the downlink signal for a particular carrier
to the proper remote antenna unit or units 716. In deployments
where more than one simulcasting configuration may be desired, the
RF connection matrix 704 (e.g., 704A, 704B) must be provisioned to
handle all possible simulcast and de-simulcast scenarios.
Furthermore, in deployments where it is desired to dynamically
change the simulcasting and de-simulcasting configurations, the RF
connection matrix 704 (e.g., 704A, 704B) will need to be
provisioned with all possible simulcast and de-simulcast scenarios
in order for the RF connection matrix 704 (e.g., 704A, 704B) to be
able to dynamically adjust according to network traffic
dynamics.
In some instances, the programming for the RF connection matrix 704
(e.g., 704A, 704B) may interface with programming at the base
station controller 708, so that it can dynamically switch between
various simulcasting and de-simulcasting configurations as needed
to accommodate traffic dynamics. Such an interface is depicted in
FIG. 7 as interface 720. In some instances, such an interface 720
between the RF connection matrix 704 (e.g., 704A, 704B) and the
base station controller 708 may be handled manually by the
operator.
In some instances, the remote antenna units 716 may be located at
varying distances from the RF connection matrix 704. Some remote
antenna units 716 may be located relatively close to the RF
connection matrix 704, while others are relatively distant
therefrom. Accordingly, in a system where multiple remote antenna
units 716 are utilized for simulcasting, the propagation delay for
the downlink signal to arrive at a distant remote antenna unit 716
might be significantly longer than the propagation delay for the
same downlink signal to arrive at the remote antenna unit 716 in
closer proximity. During simulcast, it is intended that the same
signal be transmitted by each remote antenna unit 716 at the same
or substantially the same time. However, if large differences in
the length of fiber optic cables (e.g., optic cables 806 in FIG. 8,
optic cables 910 in FIG. 9) to each remote antenna unit 716 exist,
it may be difficult to synchronize the transmissions, and a delay
spread among the simulcast antennas can go beyond the design
specifications of the access terminals served by the simulcasting
remote antenna units 716. Accordingly, in at least some examples a
suitable extra path length may be added at the shorter paths, such
as extra lengths of fiber, resulting in an equivalent path length
for the simulcasted signals.
According to another feature of the present disclosure, a base
station simulcast controller module may be implemented as part of a
processing system 600 to facilitate simulcasting downlink
transmissions according to one or more of the features described
herein, such as those described above with reference to FIGS. 2-5.
Such a base station simulcast controller module can enable base
stations to simulcast downlink transmissions without employing an
RF connection matrix. The base station simulcast controller module
may be integrated as part of the processing system 600, such as by
being integrated into the base station in some examples. In other
examples, the base station simulcast controller module may be
implemented as its own processing system 600 adapted to communicate
with a plurality of base stations.
FIG. 11 is a block diagram illustrating select components of a base
station including an integrated base station simulcast controller
module according to at least one example. That is, FIG. 11
illustrates an example where a processing system is configured as a
base station including the base station simulcast controller module
integrated as part of the processing system. The illustrated
example shows a macro-cell deployment in which multiple base
station sectors may be implemented in one form factor rack unit or
channel card. Further, the illustrated example shows a single
carrier architecture, wherein each of the base station sectors
provides communication within the same carrier frequency as one
another. However, those of ordinary skill in the art will
understand that the modem block may be provisioned to provide
multiple carriers, and may be provisioned to implement differing
simulcasting group configurations for different carriers as
described herein above.
In the illustrated system, a base station 1102 may be utilized
alone or in conjunction with one or more additional different base
stations the same as base station 1102 or different from base
station 1102 in a wireless communication system to enable multiple
access wireless communication.
The base station 1102 may include a backhaul interface 1104
enabling backhaul communication with one or more network nodes,
such as a base station controller 1106. The base station controller
1106, which may manage general call processing functions, may
additionally be communicatively coupled to one or more additional
base stations (not illustrated) over similar or different backhaul
connections, and may further be communicatively coupled to other
network nodes suitable for use in a wireless communication system,
such as the Internet 1108.
Further, the base station 1102 may include a base station modem
block 1110 including a plurality of base station sector controllers
1112A, 1112B, and 1112C and a base station simulcast controller
module 1114. Such a base station simulcast controller module 1114
may also be characterized as a transmit routing and delay
correction entity. According to at least one example, the base
station simulcast controller module 1114 may be implemented at
least in part by a processing circuit. For instance, the processing
circuit 602 of FIG. 6, alone or in conjunction with the
simulcasting group distribution operations 614 in the storage
medium 606, can be employed to implement the base station simulcast
controller module 1114.
The base station sector controllers 1112A, 1112B, and 1112C each
include sufficient circuitry for transmitting a downlink and
receiving an uplink for one sector in the wireless communication
system, and may further each include circuitry for user scheduling,
for determining a packet transmission format, and for waveform
convolution. Here, the illustrated base station modem block 1110
includes three base station sector controllers 1112, but in various
aspects of the present disclosure a base station modem block may
include any suitable number of base station sector controllers
1112.
Still further, the base station 1102 includes a plurality of base
station antenna ports 1116A, 1116B, and 1116C for interfacing with
respective remote antenna units 1118A, 1118B, and 1118C. Again,
while the illustrated base station 1102 includes three base station
antenna ports, in various aspects of the present disclosure a base
station 1102 may include any suitable number of base station
antenna ports, which may or may not necessarily exactly correspond
to the number of base station sector controllers in the base
station 1102.
According to various aspects of the present disclosure, the base
station simulcast controller module 1114, included in the base
station 1102, enables simulcasting and de-simulcasting utilizing
the plurality of remote antenna units 1118A, 1118B, and 1118C
without the need for the RF connection matrix. That is, the base
station sector controllers 1112A, 1112B, and 1112C each include a
transmit interface and a receive interface. The transmit interface
of each base station sector controller 1112 is communicatively
coupled to the base station simulcast controller module 1114, which
processes the respective transmit signals as described below for a
particular simulcast configuration and accordingly provides the
processed transmit signals to one or more respective base station
antenna ports 1116A, 1116B, and 1116C. In the illustrated example,
the remote antenna units 1118A and 1118B are employed as a
simulcasting group for simulcasting downlink transmissions for base
station sector 1 on a particular carrier, while remote antenna unit
1118C is employed for de-simulcast transmissions for base station
sector 2 on the same carrier. Group configurations for other
carriers are omitted for clarity, but they may differ from the
group configuration illustrated for the particular carrier.
On the other hand, the receive interface of each base station
sector controller 1112 can be communicatively coupled to a
respective base station antenna port 1116 without passing the
received signals through the base station simulcast controller
module 1114. In this way, aspects of the present disclosure enable
the base station modem block 1112 to decouple uplink transmissions
from downlink transmissions so that uplink capacity can be
improved. That is, in accordance with an aspect of the present
disclosure, even when a plurality of the remote antenna units 1118
are configured for simulcasting of downlink (forward link)
transmissions, the reception of uplink (reverse link) transmissions
are handled separately so that the uplink transmissions can be
either simulcasted or de-simulcasted independent of whether the
downlink transmissions are simulcasted or de-simulcasted. In this
way, simulcasting of the downlink can improve the signal to
interference and noise ratio (SINR) for an access terminal served
by the simulcasted downlinks, while the uplink can additionally be
improved with uplink diversity.
FIG. 12 is a block diagram detail view showing substantially the
same architecture as illustrated in FIG. 11 for a DAS in accordance
with an aspect of the present disclosure. Objects in FIG. 12 with
the same number as objects in FIG. 11 are the same as those already
described, so will not be described in detail with respect to this
figure. In the illustration, it can be seen that with this
architecture, which replaces the RF connection matrix 704 described
above with reference to FIGS. 7-9, connection from the base station
1102 to the remote antenna units 1118 may be simplified. That is,
the base station antenna ports 1116 of one or more base stations
1102 may be controlled by the base station controller 1106, which
communicates with the respective base stations 1102 over the
backhaul interface 1104. While the base stations 1102 with their
respective base station modem blocks 1112 are not illustrated, the
bus illustrated by the backhaul interface 1104 can be taken to
imply that any number of base stations 1102, such as the base
station 1102 illustrated in FIG. 11, are in communication with the
base station controller, where each respective base station 1102
includes a base station simulcast controller module 1114, one or
more base station sector controllers 1112, and one or more base
station antenna ports 1116.
As seen in FIG. 12, the interface between respective base station
antenna ports 1116 and a central hub 1202 including corresponding
O/E interfaces is simplified, as compared to the examples utilizing
the RF connection matrix 704 depicted in FIGS. 8 and 9. For
instance, as illustrated in FIG. 8, simulcasting might be
accomplished by way of RF combining 810. However, simulcasting can
be accomplished by the above-described features of the base station
simulcast controller module 1114, so RF combining 810 is not
required. That is, only one RF connection is required per downlink
between each base station antenna port 1116 and O/E interface at
the central hub 1202.
Additionally, the interface between respective O/E interfaces at
the central hub 1202 and the remote antenna units 1118 is
simplified, as compared to the examples utilizing the RF connection
matrix 704. For instance, as illustrated in FIG. 8, simulcasting
with the RF connection matrix 704A might be accomplished by way of
fiber combining 806C. However, as noted, simulcasting can be
accomplished by the above-described features of the base station
simulcast controller module 1114, so fiber combining 806C is not
required. That is, only one optic fiber 1204 can be employed per
downlink between the central hub 1202 including the O/E interfaces
and the remote antenna units 1118 including the E/O interfaces.
In a further aspect of the present disclosure, for each connection
between an O/E interface at the central hub 1002 and a respective
E/O interface at a remote antenna unit 1118, the optic fiber 1204
may include one single-mode fiber per downlink and one single-mode
fiber per uplink. In this way, each link for sending uplink
transmission signals from a remote antenna unit 1118 to the hub
1202 may be de-simulcast, while each link for sending downlink
transmission signals from the hub 1202 to a remote antenna unit
1118 can be either simulcast or de-simulcast, as controlled by the
base station simulcast controller module 1114.
In yet another aspect of the present disclosure, by virtue of a
function of the base station simulcast controller module 1114, the
use of extra lengths of fiber as discussed above to address the
variable delays for distant remote antenna units, can be
eliminated. That is, here, the lengths of the optic fibers 1204 may
still vary greatly, and thus, signals transmitted from a central
hub 1202 may still exhibit disparate propagation delays in
accordance with the differences in length. However, the base
station simulcast controller module 1114 may implement buffering
for delay correction so that remote antenna units 1118 which are to
participate in transmit simulcasting can be synchronized. That is,
within the base station simulcast controller module 1114, delays
may be adjusted to improve simulcast performance by compensating
for fiber-to-antenna delays. Here, delays may be cleanly controlled
by software and/or hardware in the base station simulcast
controller module 1114, for example, by digital buffering
circuitry, to compensate for variable propagation delays. Further,
because the digital buffering may be easily adjusted, corrections
to delay amounts or changes in delay amounts when a remote antenna
unit 1118 is relocated, for example, may be made.
Employing the base station simulcast controller module 1114 to
compensate for variable propagation delays, instead of using extra
lengths of fiber, can provide substantial improvements to signal to
interference and noise ratios (SINR). For instance, it has been
discovered that when the relative delay is controlled within one
(1) to two (2) chips, where one (1) chip is about 0.8
micro-seconds, then the signal to interference and noise ratio
grows linearly with the ratio of total received power from
simulcasting antennas to total received power from network.
However, if the delay is left to the fiber, then there can be
significant loss from the optimal simulcasting signal to
interference and noise ratio.
By including the base station simulcast controller module 1114 as
described above, the distribution (i.e., configuration) of
simulcasting groups can be readily modified to facilitate wireless
transmissions for a given traffic scenario at a particular time.
Further, the base station 1102 may be capable of dynamically
selecting between simulcasting and de-simulcasting distributions
for downlink transmissions as needed in accordance with one or more
network traffic parameters. That is, at some times, based on at
least one network traffic parameter (e.g., a traffic scenario, a
network interference topology), improvements in coverage of certain
locations may be desired, and thus, that location may be served by
simulcasting a downlink from several remote antenna units in that
area. Further, at some times, improvements in capacity at certain
locations may be desired, and thus, that location may be served by
de-simulcasting multiple downlinks from the remote antenna units in
that area and/or by redistributing the simulcasting configuration
to provide additional sectors for that location. Here, because the
change of the routing to the appropriate remote antenna unit 1118
is done electronically and internally to the base station 1102,
there is no longer a need for provisioning all possible
simulcasting configurations in advance, as was required when
utilizing the RF connection matrix. That is, the base station
simulcast controller module 1114 provides for improved granularity
in the selection of a simulcasting configuration in that
potentially every combination of simulcasting and de-simulcasting
of the available remote antenna units 1118 may be implemented by a
simple software command.
At least one feature of the present disclosure includes methods
operational on a base station. FIG. 13 is a flow diagram
illustrating at least one example of a method operational on a base
station. Referring to FIG. 13 together with FIG. 11, a base station
1102 can transmit, at step 1302, downlink transmissions over a
plurality of remote antenna units 1118 (e.g., 1118A, 1118B, 1118C),
where at least two of the remote antenna units 1118 (e.g., 1118A
and 1118B) are employed for simulcasting downlink transmissions as
a simulcasting group. The remote antenna units can be
communicatively coupled to the antenna ports 1116 (e.g., 1116A,
1116B, 1116C).
According to at least one example, the base station simulcast
controller module 1114 can be adapted to transmit downlink
transmissions over a plurality of remote antenna units 1118
communicatively coupled to respective base station antenna ports
1116. In some examples, the base station simulcast controller
module 1114 may be adapted to facilitate downlink simulcasting by
enabling electronic splitting of a transmit signal from a base
station sector controller 1112 to be provided to any number of the
base station antenna ports 1116. The base station simulcast
controller module 1114 can provide the electronically split
transmit signal to each of the remote antenna units 1116 employed
for simulcasting the transmit signal.
In some examples, the base station simulcast controller module 1114
can be adapted to simulcast downlink transmissions according to the
features described herein with reference to FIGS. 2 and 3 above.
For instance, the base station simulcast controller module 1114 can
be adapted to simulcast the downlink transmissions on a first
carrier over a first group of two or more remote antenna units 1118
employing a particular sector ID, while simulcasting downlink
transmissions on a second carrier over a second group of two or
more remote antenna units 1118 employing the same sector ID. In
such an example, at least one remote antenna unit 1118 of the
second group may differ from the remote antenna units 1118 of the
first group. The base station simulcast controller module 1114 can
further modify which remote antenna units 1118 are included in the
first group and/or the second group, as described in more detail
below.
In some examples, the base station simulcast controller module 1114
can be adapted to simulcast downlink transmissions according to the
features described herein with reference to FIGS. 4 and 5 above.
For instance, the base station simulcast controller module 1114 can
be adapted to simulcast the downlink transmissions over the
plurality of remote antenna units 1118 where at least one remote
antenna unit 1118 is positioned so that a coverage area associated
with this at least one remote antenna unit 1118 is not adjacent to
a coverage area associated with any of the other remote antenna
units 1118 of the plurality. The base station simulcast controller
module 1114 can further modify which remote antenna units 1118 are
included in the simulcasting group, as described in more detail
below.
According to at least some examples, the base station 1102 can be
further adapted to receive uplink transmissions over the plurality
of remote antenna units that are de-simulcasted, even when downlink
transmissions are simulcasted. For example, the base station sector
controllers 1112A, 1112B, and 1112C can each include a transmit
interface and a receive interface. The transmit interface can be
communicatively coupled to the base station simulcast controller
module 1114 for facilitating simulcasted downlink transmissions,
and the receive interface can be communicatively coupled to a
respective base station antenna port 1116 without passing the
received signals through the base station simulcast controller
module 1114. Accordingly, even when a plurality of the remote
antenna units 1118 are configured for simulcasting of downlink
(forward link) transmissions, the reception of uplink (reverse
link) transmissions from the plurality of remote antenna units 1118
are handled separately so that the uplink transmissions can be
de-simulcasted independent of whether the downlink transmissions
are simulcasted or de-simulcasted.
At step 1302, the base station 1102 can obtain one or more network
traffic parameters. For example, the base station simulcast
controller module 1114 may be adapted to obtain the one or more
network traffic parameters. In some instances, the base station
1102 can obtain the one or more network traffic parameters by
receiving a communication from the base station controller 1106. As
a result of the base station 1102 being adapted to communicate with
the base station controller 1106 by way of the backhaul interface
1104, knowledge of network traffic parameters, such as traffic
usage and loading, can be readily exchanged to change the
simulcasting configuration when such a change would be beneficial.
This can occur within carriers over time, or between carriers. In
some examples, the base station controller 1106 can determine a
suitable group distribution (e.g., configuration) of some
simulcasting remote antenna units and some de-simulcasting remote
antenna units, in accordance with the traffic scenario, by
communicating directly with the base station 1102. For instance,
the base station controller 1106 may monitor traffic usage across
the remote antenna units 1118, and may utilize this information to
optimally apply simulcasting and de-simulcasting in accordance with
the traffic usage. In this example, the base station controller
1106 may provide network traffic parameters in the form of commands
or instructions to the base station 1102. The base station 1102
(e.g., the base station simulcast controller module 1114) can
thereby readily change the simulcasting group distributions in
accordance with these instructions.
In other examples, the base station controller 1106 may provide the
network traffic parameters in the form of traffic information to
the base station simulcast controller module 1114 by way of the
backhaul connection 1104, and the base station simulcast controller
module 1114 may utilize this traffic information to make a
determination regarding a change of the simulcasting configuration
internally in accordance with the received traffic information.
That is, the base station simulcast controller module 1114 may be
adapted to make a determination relating to a change in the routing
path of the transmit signal based on received information
corresponding to traffic usage.
In response to the one or more network traffic parameters, the base
station 1102 can modify the simulcasting group configuration(s) at
step 1306. For example, the base station 1102 (e.g., the base
station simulcast controller module 1114) can modify a simulcasting
group to include at least one different remote antenna unit 1118
for simulcasting downlink transmissions. That is, the base station
simulcast controller module 1114 can remove and/or add one or more
remote antenna units 1118 included in a simulcasting group. In some
examples, the base station simulcast controller module 1114 may be
adapted to modify a simulcasting group by changing the routing path
of a transmit signal received from a base station sector controller
1112 to transmit to a different remote antenna port 1116 for
simulcasting downlink transmissions.
As noted above, some configurations for a base station simulcast
controller module include the base station simulcast controller
module implemented as its own processing system 600 adapted to
communicate with a plurality of base stations. FIG. 14 is a block
diagram illustrating select components of a distributed antenna
system (DAS) employing a base station simulcast controller module
1402 implemented as a processing system adapted to communicate with
a plurality of base stations. Configurations such as the one
depicted by FIG. 14 may be suitable for implementing a distributed
antenna system (DAS) with a plurality of base stations employed as
pico cells 1404 (e.g., 1404A, 1404B, and 1404C). That is, the base
station simulcast controller module 1114 illustrated in FIG. 11 is
integrated into a base station 1102 that may generally be referred
to as a macro cell, in which it is common to implement a plurality
of base station sectors, e.g., by including the base station sector
controllers 1112. On the other hand, a pico cell 1404 (e.g., 1404A,
1404B, and 1404C) may typically include a controller for one or two
base station sectors. In the illustration of FIG. 14, each pico
cell 1404A, 1404B, 1404C is shown as a single-sector base station,
although aspects of the present disclosure can apply to
multi-sector pico cells.
With this architecture, since the pico cells 1404 are separated,
the architecture including a central base station simulcast
controller module 1114 from FIG. 11 does not necessarily apply.
Still, in accordance with various aspects of the present
disclosure, some coordination for simulcasting of downlink
transmissions through the backhaul connecting the pico-cells 1404
together may be desired. It should be understood that when
reference is made below to one or more functional aspects of the
base station simulcast controller module 1402, such functional
aspects can be implemented by a processing circuit of the base
station simulcast controller module 1402, such as the processing
circuit 602 implementing the simulcasting group distribution
operations 614 shown in FIG. 6.
In accordance with an aspect of the present disclosure, the
architecture illustrated in FIG. 14 includes a base station
simulcast controller module 1402, which is communicatively coupled
to a plurality of single-sector base stations 1404A, 1404B, and
1404C and to a base station controller 1406. The base station
simulcast controller module 1402 can be communicatively coupled
through a first backhaul interface 1408 to the plurality of
single-sector base stations 1404A, 1404B, and 1404C, for example,
utilizing a very low latency and low bandwidth connection
configured for simulcasting control. The base station simulcast
controller module 1402 can be communicatively coupled to the base
station controller 1406 and to the plurality of base stations 1404
by means of a communications interface, such as the communications
interface 604 described above with referent to FIG. 6.
The base station controller 1406 may also be communicatively
coupled with the respective base stations 1404 through a second
backhaul interface 1410. Here, the second backhaul interface 1410
may be a low latency connection for conventional communication of
uplink and downlink packets between the base station controller
1406 and the base stations 1404.
The base station simulcast controller module 1402 may be adapted to
provide the respective base stations 1404 over the first backhaul
interface 1408 with simulcasting control instructions or commands
to implement simulcasting or de-simulcasting, as needed, from the
respective base stations 1404. The simulcasting control
instructions may be in accordance with one or more obtained traffic
parameters (e.g., traffic usage information provided by the base
station controller 1406). Further, the base station simulcast
controller module 1402 may direct the base station controller 1406
to send the same downlink packets across two or more base stations
1404 in simulcast, where the two or more base station 1404 all use
the same sector identity (ID) for the simulcast. As illustrated, a
first base station 1404A is configured for de-simulcasting the
downlink transmission from its sector (e.g., sector 1), and a
second base station 1404B and third base station 1404C are
configured to simulcast a downlink transmission for a different
sector (e.g., sector 2). Of course, the base station simulcast
controller module 1402 may configure the respective base stations
1404 to any suitable simulcasting configuration in accordance with
various aspects of the present disclosure. Additionally, the
depicted configuration may be implemented for a one carrier, while
a different simulcast/de-simulcast configuration may be implemented
for a different carrier, such that different carriers employ
different grouping configurations.
In a further aspect of the present disclosure, when a plurality of
base stations such as the second base station 1404B and the third
base station 1404C are configured for simulcast, the base station
simulcast controller module 1402 may select one of the plurality of
simulcasting base stations 1404B or 1404C to be a master, so that
the other base station(s) in simulcast will be slave(s). Here, the
selected master base station in the simulcast group may run a
scheduler, and may select which users will be served. Further, the
base station simulcast controller module 1402 may ensure that users
selected by the master base station are known to the slave base
station(s), so that all simulcasting base stations properly format
the same user packet selected for transmission across the
simulcasting base stations.
In this architecture, since all base stations 1404 and the base
station simulcast controller module 1402 are directly communicating
with the base station controller 1406, which manages general call
processing, the knowledge of traffic usage and loading can be
readily exchanged to dynamically change the simulcasting
configuration when needed.
As described herein above, the uplink signals may operate
separately from each base station 1404, to improve the capacity for
uplink transmissions from access terminals to the respective base
stations 1404. Further, since the modem at each base station 1404
may operate across multiple carriers, this architecture enables
independent simulcasting configurations to occur between carriers,
as well as dynamically changing simulcasting configuration across
carriers over time. In general, the present architecture including
the base station simulcast controller module 1402 can be employed
for implementing any of the various simulcasting distributions
described herein above with reference to FIGS. 2-5, except that one
or more of the remote antenna units in those examples can be
implemented by base stations 1404 in the present example. That is,
the base station simulcast controller module 1402 can be adapted to
select the simulcasting base stations 1404 to implement any of the
features and configurations described above with reference to FIGS.
2-5.
In yet a further aspect of the present disclosure, the architecture
illustrated in FIG. 14 utilizes communication interfaces over the
respective backhaul interfaces 1410 and 1408, such that
RF-over-fiber connections for coupling the base station 1404 to
distant remote antenna units are not needed. Thus, special
circuitry to process differential propagation delays over
variable-length optic fiber cables may not be necessary in this
architecture. Nonetheless, due to differences in distance for the
propagation of the backhaul signal over the second backhaul
interface 1410, at least one of the base station simulcast
controller module 1402 or the base station controller 1406 may be
provisioned to suitably handle variable delays so that the
simulcasted signals from the respective base stations 1404 are at
least substantially synchronized.
Further aspects of the present disclosure are related to methods
operational for a base station simulcast controller module, such as
the base station simulcast controller module 1402. FIG. 15 is a
flow diagram illustrating at least one example of such a method.
Referring to FIGS. 14 and 15, a base station simulcast controller
module 1402 may send a message to a base station controller to
direct the base station controller to send the same downlink
packets across each of a plurality of base stations for simulcast
with a common (i.e., the same) sector identity (ID), at step 1502.
For example, a processing circuit (e.g., the processing circuit 602
implementing the simulcasting group distribution operations 614
shown in FIG. 6) can be adapted to generate and transmit the
message to a base station controller 1406 to direct the base
station controller 1406. The transmitted message may also identify
the sector ID to be employed by the plurality of remotely deployed
base stations.
According to various features, the processing circuit may be
adapted to select the plurality of base stations in accordance with
the various features described above with reference to FIGS. 2-5.
For example, the processing circuit may be adapted select the
plurality of base stations to include a first group of two or more
base stations for simulcasting downlink transmissions on a first
carrier with a sector ID, and a second group of two or more base
stations for simulcasting downlink transmissions on a second
carrier with the same sector ID. At least one base station of the
second group can differ from the two or more base stations making
up the first group. In another example, the processing circuit can
be adapted to select the plurality of base stations to include at
least one base station that is located so that a coverage area
associated with that at least one base station is not adjacent to a
coverage area associated with any of the other base stations of the
plurality.
At step 1504, the base station simulcast controller module 1402 can
send one or more simulcasting control instructions to the plurality
of base stations. The one or more simulcasting control instructions
may be adapted for facilitating simulcasting from the plurality of
base stations. In at least one example, the processing circuit
(e.g., the processing circuit 602 implementing the simulcasting
group distribution operations 614 of FIG. 6) can be adapted to send
the one or more simulcasting control instructions to the plurality
of base stations 1404 over a backhaul interface 1408.
In some implementations, the base station simulcast controller
module 1402 may obtain one or more network traffic parameters, as
indicated by step 1506. For example, the processing circuit (e.g.,
the processing circuit 602 implementing the simulcasting group
distribution operations 614 in FIG. 6) may obtain traffic
parameters, such as a traffic scenario or a network interference
topology. The processing circuit may obtain such network traffic
parameters from the base stations 1404, the base station controller
1406, or a combination thereof.
At step 1508, the base station simulcast controller module 1402 can
implement or modify simulcasting at the plurality of base stations
in response to the one or more traffic parameters. For instance,
the processing circuit (e.g., the processing circuit 602
implementing the simulcasting group distribution operations 614 in
FIG. 6) may evaluate the network traffic parameters and/or an
instruction associated with the network traffic parameters and
responsively implement or modify a simulcasting configuration
according to those traffic needs.
According to one or more other implementations, a method may also
include steps for selecting a master base station and one or more
slave base stations, as described above, and/or synchronizing the
downlink transmissions from the plurality of base stations. Such
additional or alternative steps can be carried out by the
processing circuit (e.g., the processing circuit 602 implementing
the simulcasting group distribution operations 614 in FIG. 6).
One or more of the components, steps, features and/or functions
illustrated in FIGS. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14
and/or 15 may be rearranged and/or combined into a single
component, step, feature or function or embodied in several
components, steps, or functions. Additional elements, components,
steps, and/or functions may also be added without departing from
the scope of the present disclosure. The apparatus, devices and/or
components illustrated in FIGS. 1, 4, 6, 7, 8, 9, 11, 12 and/or 14
may be configured to perform one or more of the methods, features,
or steps described in FIGS. 2, 3, 4, 5, 10, 13 and/or 15. The novel
algorithms described herein may also be efficiently implemented in
software and/or embedded in hardware.
Also, it is noted that at least some implementations have been
described as a process that is depicted as a flowchart, a flow
diagram, a structure diagram, or a block diagram. Although a
flowchart may describe the operations as a sequential process, many
of the operations can be performed in parallel or concurrently. In
addition, the order of the operations may be re-arranged. A process
is terminated when its operations are completed. A process may
correspond to a method, a function, a procedure, a subroutine, a
subprogram, etc. When a process corresponds to a function, its
termination corresponds to a return of the function to the calling
function or the main function.
Those of skill in the art would further appreciate that the various
illustrative logical blocks, modules, circuits, and algorithm steps
described in connection with the embodiments disclosed herein may
be implemented as hardware, software, firmware, middleware,
microcode, or any combination thereof. To clearly illustrate this
interchangeability, various illustrative components, blocks,
modules, circuits, and steps have been described above generally in
terms of their functionality. Whether such functionality is
implemented as hardware or software depends upon the particular
application and design constraints imposed on the overall
system.
The terms "machine-readable medium", "computer-readable medium",
and/or "processor-readable medium" may include, but are not limited
to portable or fixed storage devices, optical storage devices, and
various other non-transitory mediums capable of storing, containing
or carrying instruction(s) and/or data. Thus, the various methods
described herein may be partially or fully implemented by
instructions and/or data that may be stored in a "machine-readable
medium", "computer-readable medium", and/or "processor-readable
medium" and executed by one or more processors, machines and/or
devices.
The various features of the embodiments described herein can be
implemented in different systems without departing from the scope
of the disclosure. It should be noted that the foregoing
embodiments are merely examples and are not to be construed as
limiting the disclosure. The description of the embodiments is
intended to be illustrative, and not to limit the scope of the
claims. As such, the present teachings can be readily applied to
other types of apparatuses and many alternatives, modifications,
and variations will be apparent to those skilled in the art.
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